Constructing oxygen vacancy-enriched Fe2O3@NiO heterojunctions for highly efficient electrocatalytic alkaline water splitting

Abstract

Electrolysis of water to produce high-purity hydrogen is a very promising method. The development of green, high-efficiency, long-lasting and low-cost dual function electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is essential for electrocatalytic total water splitting. In this work, oxygen vacancy-enriched Fe₂O₃@NiO heterojunctions as bifunctional electrocatalysts are prepared through a facile one-step hydrothermal method followed by a calcination process. The synergistic effect of Fe₂O₃ and NiO, as well as the rich oxygen vacancies in Fe₂O₃, optimize their electronic structures, leading to an enhanced charge transfer rate and improved catalytic ability. Therefore, in both OER and HER processes, overpotentials needed for the Fe₂O₃@NiO catalyst to achieve the current density of 10 mA cm⁻² under alkaline conditions are 224 mV and 187 mV, respectively. Furthermore, the catalyst showed excellent dynamic characteristics and durability. This research provides a new strategy for regulating the electronic structure of bifunctional catalysts by heterostructures and oxygen vacancies, thereby promoting the performance of total water splitting.